Atomic Layer Deposition in Nanoporous Catalyst Materials - Atomically-Precise Methods for Synthesis of Solid Catalysts - page 191

d n 9 r 4 n g | 7

Figure 7.19 Photocatalytic degradation of methylene blue on a blank mesoporous
silica film, a mesoporous silica film loaded with anatase nanoparticles,
and a planar TiO 2 /Si sample.
Adapted from ref. 51.

particle size estimations from XRD patterns indicated an increasing trend in
anatase particle size with increasing TiO 2 deposition in similar mesoporous
silica films.

7.4 Conclusions
Atomic layer deposition (ALD) is discussed as a promising method for sup-
ported catalyst preparation. The self-saturation of the chemical surface re-
actions in ALD enables the conformal coating of high surface area
nanoporous materials and provides atomic-level control over the coating
thickness. These unique advantages offer ALD the ability to precisely control
the pore size and chemical surface composition of nanoporous materials,
and therefore render ALD an effective method for the nanoscale design of
catalysts. As illustrated with selected examples from literature and two case
studies, a wide variety of oxides, metals and other materials can be deposited
on the interior surface of nanoporous supports, resulting in catalytic active
materials. This can be either as an ultra-thin conformal layer or, if growth is
inhibited during nucleation, as dispersed nanoparticles. Nanosized particles
can also be fabricated by the controlled breakup of an ALD-deposited layer
through calcination, as demonstrated here for the formation of anatase
nanoparticles. Because of its versatility and exceptional growth control, the
ALD technology has attracted attention from researchers in various fields
such as photocatalysis and acid catalysis, and is also particularly relevant to
the synthesis of model catalysts and microchannel reactors used for
screening purposes. While gram quantities of catalyst support material can
be generally treated in ALD research labs, the optimization and scale-up of

.